One of the main points of interest in comparing trees is to interpret them as explaining the evolution of a fixed set of labels under some “agglomerative” criterion, being it a clustering criterion or a genetic evolution summary. For this reason, a lot of research focused on comparing labelled trees. The most notable examples of metrics for weighted labelled trees are the Robinson-Foulds metric [1]} and the BHV metric [2]}.
A number of limitations of these metrics has been pointed out by [3]} and [4]}. In particular, severe shortcomings prevent researchers from comparing weighted tree shapes with a variable number of leaves.
